/*
*
* 翻转二叉树
*
* */

class Solution {
    public TreeNode invertTree(TreeNode root) {
       if(root==null){
           return null;
       }
        TreeNode  tmp=root.left;
        root.left=root.right;
        root.right=tmp;
        invertTree(root.left);
        invertTree(root.right);
        return root;

        

    }
}